“This pilgrim, in divesting himself of fear, is not at all fanatical or ignorant, since he gives good reason for his attitude. ‘I will fear no evil,’ says he, ‘for thou art with me.’ Was there ever a better reason given under Heaven for being fearless than this—that God is with us? He is on our side. He is pledged to help us. He has never failed us. Where, then, is there room for terror when the omniscient, immutable God is on our side?
Let the heavens be dissolved, and the earth be melted with fervent heat, but let not the Christian’s heart be moved: let him stand like the great mountains, whose foundations are confirmed for ever, for the Lord God will not forsake His people or break His covenant. ‘I will fear no evil: for thou art with me.’
There is something more here than freedom from fear and a substantial reason for it, for the true believer rejoices in exalted companionship. ‘Thou art with me.’ Thou—Thou—Thou—the King of kings, before Whom every seraph veils his face. ‘Thou art with me.’ How brave that person ought to be who walks with the Lion of the tribe of Judah as his guard!”
–Charles H. Spurgeon, “The Valley of the Shadow of Death,” The Journal of Biblical Counseling, Vol. 18, No. 3, 2000, p. 34.